Control for engine cooling blowers



Patented Nov. 23, 1948 4 CONTROL FOR ENGINE COOLING BLOWERS John G. Lee, Farmington, Conm, assignor to United Aircraft Corporation. East Hartford, Conn., a corporation of Delaware Application June 7, 19, Serial No. 539,218

3 Claims. (Cl. 230-114) This invention relates to aircraft, and more particularly, to the engine cooling systems therefor. Aircraft engines are enclosed in a cowl which is open to the atmosphere at its ends so that the travel of the airplane will cause air to enter the cowl, pass over the engine to effect cooling thereof and discharge through the rear opening. In certain types of aircraft, the amount of cooling air thus provided is insuiiicient for most operating conditions unless a booster in the form of a blower is provided within the cowl to force more air therethrough. The fan may be positioned either at the front or rear of the engine.

For different operating conditions, suchas different altitudes, it is desired that the fan shall be effective to the desired degree for the particular operating condition. Therefore, it is one of the principal objects of this invention to provide controllable means for varying the effectiveness of the fan.

It is a further object of this invention to vary the effectiveness of the fan by varying the amount of air directed toward the fan.

One of the undesirable characteristics of fans is a stall or flow-breakaway condition, which usually results from too small an axial velocity relative to the optimum value for which the fan was designed. This condition can be eliminated if the velocity through the fan could be maintained high even though the quantity of air passing the fan is reduced. To provide these conditions a variable area of exposed fan blades becomes desirable. It is therefore a further object of this invention to vary the effectiveness of the fan and; avoid the stall condition by varying the working area of the fan.

Further objects and advantages of this invention will become apparent in the following detailed description thereof,

In the accompanying drawings:

Figure 1 is an elevation, largely diagrammatic, and with part of the engine cowl broken away, showing one form of this invention as applied to a tractor type airplane;

Fig. 2 is a view similar to Fig. 1 showing another form of this invention applied to a pusher type airplane; and

Figs. 3, 4 and 5 are views similar to Fig. 2 showing still other forms of this invention.

Referring to Fig. i, there is disclosed a tracto type of airplane in which a propeller i0 and a I spinner II are rotated by an engine I! enclosed within a cowl ii at the forward end of the fuselage or engine nacelle it. The cowlis open at its forward end I! so that the travel of the airplane will cause air to enter the cowl, pass over and cool the engine, and discharge through a rear passage is between the cowl and the main fuselage. The amount of cooling air passini through the cowl and over the engine due to the movement of the airplane would be insuiiicient under most operating conditions, and therefore a fan 2'! is provided, said fan being driven from the engine and adapted to force the air through the cowl. More air can thusbe passed through the cowl than would be the case if the movement of the airplane alone were relied upon to force the air into opening ll.

As stated in the introduction hereto, it is not always desired that the full eflect of the fan shall be exerted under all operating conditions. Thus. for example, at lower altitudes less output from the fan is desired than at higher altitudes. Therefore this invention provides means for vary-. ing the effectiveness of the fan, Such variation may be controlled by an operator or it may be automatically controlled in accordance with variations of some factor such as altitude or engine temperature. For this purpose there is provided in combination with the fan, means for controlling the amount of air delivered to the fan and for controlling the effective area of the fan. In Fig. I there is shown one such means in the form of a plurality of flaps l0 pivoted at their forward ends on the cowl at 3| adjacent the opening l1 and having their rearward ends terminating adjacent the fan 28. By causing the rearward ends of said flaps to converge, the opening for the entering air is reduced so that a lesser quantity of air enters the cowl, and, further, part of the fan is cut off from eflective contact with the entering air. Thus simultaneously there is effected a two-way control of the cooling air passing through the cowl-the amount of air entering the cowl is controlled and the effective area of the fan acting upon this quantity of air is also controlled at the same time and by the same means.

This invention is capable of embodiment in various forms and to various types of airplanes. Thus, in Figs. 2 to 5 certain forms of this invention are shown applied to pusher type aircraft but it will be understood that the principles involved apply equally well to tractor types of airplanes. In Fig. 2, the propeller I0 is shown atthe rear of the craft, driven by the engine if enclosed in cowl it, through a shaft and gear reduction unit 44. In this form, the flaps 40 are pivoted at their forward ends at ll on the engine casing, the rearward ends of the flaps operatingadiacent the tan it. The action is the some as in the Fig. 1 form oi the invention.

In the Fig. 4 form, there are provided in addition to the flaps 40 01 the Fig. 2 form, flap; 42 at the rear of the fan, the latter flaps being pivoted at their rearward edges upon the gear casing 49 enclosing the gearing N and supporting the spinner H. In this form the effective area oi. the tan may be controlled at the entering and leaving sides oi the tan, and the positioning of the flaps 40 and it will determine the quantity of airv handled by the fan.

The Fig. 5 form is similar to the Fig. 4 form. but the two sets oi flaps 59' and 09, instead of being supported on the "engine casing, are both supported on the cowl it. The action is the same as in the Fig. i form except that the flaps operate in directions opposite to that oi flaps 90 and d2.

, In Fig. 3 there is disclosed a form oi this invention which does not employ flaps but instead employs an inflatable member for varying the amount of air delivered to the fan and for varying the eiiective area oi the fan. Said member may take the form of a fiexible annular tube 99 adapted to surround the engine casing in advance of the fan 29', with the aisle of the tube coincident with the axis oi rotation of the fan. Suitable connection to a source oi fluid pressure may be made so that by inflating tube 00 it will reduce the annular passage between it and the cowl i9 and at the same time cover up more of the fan so as to reduce the efiective flan area. Its action is therefore similar to that of flaps t0, t0 or 00". Ii desired, another inflatable member b2 may be provided at the rear of the fan, the member 92 being supported on the gear casing as.

In accordance with the provisions of the patent statutes, I have herein described the principle and operation of my invention. together with one embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more general results out;- lined, and the invention extends to such use,

iii

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a device of the, character described. a tan having an annular pumping region with outer and inner limits, means providing an annular opening for a stream of cooling air to reach said fan, and adjustable means comprising flaps pivoted at' their forward ends and terminating adjacent said fan at the rearward ends of said flaps, said flaps being adapted to cut oi! a pre determined annular portion of said region.

2. In a device 0! the character described, a fan having an annular pumping region with outer and inner limits, means providing an annular opening for a stream of cooling air to reach said fan, and adjustable means comprising flaps pivoted at their forward ends and terminating adjacent said fan at the rearward ends of said naps, said flaps being adapted to out oh the outer portion of said region.

3. In a device oi the character described, a fan having an annular pumping region with outer and inner limits, means providing an annular opening for a stream of cooling air to reach said fan, and adjustable means comprising flaps pivoted at their forward ends and terminating adjacent said fan at the rearward ends of said flaps. said naps being adapted to cut ofif the inner portion 01 said region.

some G. LEE.

- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Neumann et al. Mar. 12, 1948 

